A Potential Approach to Ammonia-Hydrogen Synergy: Insights from Molecular Dynamics Simulations

Area of Science:

• Physical Chemistry
• Materials Science
• Chemical Engineering

Background:

• Hydrogen nanobubbles in liquid ammonia offer potential for ammonia-hydrogen synergy in transportation fuels.
• Understanding the fundamental mechanisms of hydrogen nanobubbles in liquid ammonia is crucial but limited by current data.

Purpose of the Study:

• Investigate the dynamic behaviors and evolution of hydrogen nanobubbles in liquid ammonia.
• Determine thermophysical properties and stability mechanisms of hydrogen nanobubbles across various supersaturation levels.

Main Methods:

• Employed molecular dynamics (MD) simulations to study hydrogen nanobubbles in liquid ammonia.
• Analyzed thermophysical properties, stability, and transport phenomena.

Main Results:

• Stable nanobubbles form within a moderate supersaturation range; low supersaturation prevents nucleation, high supersaturation causes phase separation.
• Hydrogen nanobubbles exhibit high internal pressure and density, deviating from macroscopic models.
• Nanobubbles reduce liquid ammonia viscosity but increase thermal conductivity and diffusion coefficients.
• Gas supersaturation and surface tension are key to nanobubble mechanical equilibrium.

Conclusions:

• Established optimal supersaturation range for stable hydrogen nanobubbles in liquid ammonia.
• Quantified the impact of hydrogen nanobubbles on liquid ammonia's thermophysical properties.
• Estimated a maximum achievable hydrogen-to-ammonia ratio of 9.07% for fuel applications.